CN108572408B

CN108572408B - Light source device and light filtering component thereof

Info

Publication number: CN108572408B
Application number: CN201710136956.8A
Authority: CN
Inventors: 洪健翔; 林昇旺
Original assignee: OTO Photonics Inc
Current assignee: OTO Photonics Inc
Priority date: 2017-03-09
Filing date: 2017-03-09
Publication date: 2021-09-17
Anticipated expiration: 2037-03-09
Also published as: CN108572408A

Abstract

An optical filter assembly includes a first interference film and a second interference film. The first interference film includes a plurality of first film layers and a plurality of second film layers. The first films and the second films are alternately stacked. The second interference film comprises a plurality of third film layers and a plurality of fourth film layers. The third films and the fourth films are alternately stacked. The optical constant of the first film layer is the same as that of the third film layer, the optical constant of the second film layer is the same as that of the fourth film layer, and the optical path difference generated by the first interference film is different from that generated by the second interference film.

Description

Light source device and light filtering component thereof

Technical Field

The present invention relates to a light source device and an optical filter assembly thereof, and more particularly, to an optical filter assembly using interference (interference) for filtering light and a light source device using the same.

Background

An interference filter has been developed in the optical technology. In general, an interference filter has a multilayer film (multilayered) in which two film layers (films) having different optical constants (optical constants) are alternately stacked on each other, and both of the film layers are transparent (transparent). According to the thickness distribution and the optical constants of the two film layers, light can perform constructive interference (constructive interference) and destructive interference (destructive interference) in the multilayer film, so that the interference filter can allow light with the wavelength within a specific range to pass through and filter light with the wavelength outside the specific range. However, the design limit and the manufacturing error (tolerance) of the film thickness in the multilayer film affect the filtering effect of the interference filter, so that when the interference filter is applied to an optical measurement apparatus such as a spectrometer (spectrometer), a monochromator (monochromator) or an interferometer (interferometer), the precision (precision) and the accuracy (accuracy) may be affected.

Disclosure of Invention

The invention provides an Optical filter module, which utilizes the Difference of Optical Path Difference (OPD) generated by two interference films to improve the filtering effect.

The invention further provides a light source device comprising the light filtering assembly.

The optical filter assembly provided by the invention comprises a first interference film and a second interference film. The first interference film comprises a plurality of first film layers and a plurality of second film layers, wherein the first film layers and the second film layers are stacked alternately. The second interference film comprises a plurality of third film layers and a plurality of fourth film layers, wherein the third film layers and the fourth film layers are alternately stacked. The optical constants of the first film layer are the same as those of the third film layer, and the optical constants of the second film layer are the same as those of the fourth film layer. The first interference film and the second interference film are both positioned on a transmission path of a light beam, and the optical path difference generated by the first interference film is different from the optical path difference generated by the second interference film.

The light source device provided by the invention comprises the light filtering component and a light source, wherein the light source is arranged beside the light filtering component and used for emitting light beams towards the light filtering component.

Based on the above, the optical filter assembly of the present invention utilizes the multilayer interference film with constant thickness ratio to generate different optical path differences and interferences, thereby improving the filtering effect and helping to improve the precision and accuracy.

The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical means of the present invention more clearly understood, the present invention may be implemented in accordance with the content of the description, and in order to make the above and other objects, features, and advantages of the present invention more clearly understood, the following specific examples are described in detail with reference to the accompanying drawings.

Drawings

Fig. 1A is a schematic cross-sectional view of a light source device according to an embodiment of the invention.

FIG. 1B is a schematic diagram of the spectrum (spectrum) of the light beam of FIG. 1A after passing through the first and second interference films, respectively.

FIG. 1C is a schematic diagram of the spectrum of the light beam of FIG. 1A after passing through the optical filter assembly.

Fig. 2A is a schematic cross-sectional view of a light source device according to another embodiment of the invention.

Fig. 2B is a schematic cross-sectional view of a light source device according to another embodiment of the invention.

FIGS. 2C-2I are schematic diagrams of optical film designs of interference films in another embodiment of the invention.

Fig. 3 is a schematic cross-sectional view of a light source device according to another embodiment of the invention.

Fig. 4A is a schematic cross-sectional view of a light source device according to another embodiment of the invention.

Fig. 4B is a schematic cross-sectional view of a light source device according to another embodiment of the invention.

Fig. 4C is a schematic cross-sectional view of a light source device according to another embodiment of the invention.

Fig. 5A is a schematic cross-sectional view of a light source device according to another embodiment of the invention.

Fig. 5B and 5C are spectral diagrams of the light beam in fig. 5A after passing through the first interference film and the second interference film.

Fig. 6 is a schematic cross-sectional view of a light source device according to an embodiment of the invention.

Detailed Description

Fig. 1A is a schematic cross-sectional view of a light source device according to an embodiment of the invention. Referring to fig. 1A, a light source device 10a includes a light filter assembly 100 and a light source 10. The light source 10 is disposed beside the light filter assembly 100 and is used for emitting a light beam (light beam) L1 containing a plurality of lights (ray) toward the light filter assembly 100, wherein the light source 10 is, for example, a light emitting diode or a halogen lamp. The optical filter assembly 100 is disposed on the transmission path of the light beam L1 and includes two layers of interference films. The two interference films can be manufactured using existing optical film designs, which have been disclosed in some prior art documents, such as the book written by mr. li: "thin film optics and coating technology" (ISBN: 9789863940142).

In the embodiment shown in fig. 1A, the optical filter assembly 100 includes a first interference film 110 and a second interference film 120, both of which are multilayer films. Taking fig. 1A as an example, the first interference film 110 includes a plurality of first film layers 111 and a plurality of second film layers 112, wherein the first film layer 111 has a thickness T1, and the second film layer 112 has a thickness T2. The second interference film 120 includes a plurality of third film layers 123 and a plurality of fourth film layers 124, wherein the third film layers 123 have a thickness T3 and the fourth film layers 124 have a thickness T4. The first layers 111 and the second layers 112 are stacked alternately, and the third layers 123 and the fourth layers 124 are stacked alternately.

The first film 111 and the third film 123 may be made of a high refractive index material, such as tantalum pentoxide or titanium dioxide (titanium dioxide). The second layer 112 and the fourth layer 124 may be made of a low refractive index material, such as silicon dioxide (silicon dioxide). Therefore, the first interference film 110 and the second interference film 120 are formed by alternately stacking at least two films with different optical constants, such as refractive index. In addition, the first layer 111 and the third layer 123 may be made of the same material, and the second layer 112 and the fourth layer 124 may be made of the same other material, but the material of the first layer 111 and the third layer 123 is different from the material of the second layer 112 and the fourth layer 124. Therefore, the optical constants of the first layer 111 are the same as the optical constants of the third layer 123, the optical constants of the second layer 112 are the same as the optical constants of the fourth layer 124, and the optical constants of the first layer 111 and the third layer 123 are different from the optical constants of the second layer 112 and the fourth layer 124.

The first interference film 110 and the second interference film 120 are both located on the transmission path of the light beam L1 and are penetrated by the light beam L1, wherein the light beam L1 shown in fig. 1A penetrates the second interference film 120 first and then penetrates the first interference film 110. When the light beam L1 enters the first interference film 110 and the second interference film 120, the light beam L1 is reflected and refracted at a boundary (boundary) between the layers (i.e. the first layer 111 and the second layer 112) in the first interference film 110 and at a boundary (i.e. a boundary between the third layer 123 and the fourth layer 124) in the second interference film 120 to generate interference.

It should be noted that, although the above embodiments have been described with the first film layer 111 and the third film layer 123 as high refractive index layers and the second film layer 112 and the fourth film layer 124 as low refractive index layers, in other embodiments, the first film layer 111 and the third film layer 123 may be changed to low refractive index layers, and the second film layer 112 and the fourth film layer 124 may be changed to high refractive index layers. Therefore, it is not limited that the first film layer 111 and the third film layer 123 are high refractive index layers, and it is also not limited that the second film layer 112 and the fourth film layer 124 are low refractive index layers.

In the embodiment shown in fig. 1A, the light beam L1 sequentially penetrates through the second interference film 120, the first transparent substrate 101, and the first interference film 110, but in other embodiments, the light beam L1 can also sequentially penetrate through the first interference film 110, the first transparent substrate 101, and the second interference film 120, wherein the light beam L1 sequentially penetrates through the first film 111, the second film 112, the first film 111, and the second film 112 …, or sequentially penetrates through the second film 112, the first film 111, the second film 112, and the first film 111 … in the first interference film 110, and the light beam L1 sequentially penetrates through the third film 123, the fourth film 124, the third film 123, and the fourth film 124 …, or sequentially penetrates through the fourth film 124, the third film 123, the fourth film 124, and the third film 123 … in the second interference film 120. Therefore, the order of the light beam L1 penetrating through the first film layer 111 to the fourth film layer 124 is not limited to the order shown in fig. 1A.

In addition, in the embodiment shown in fig. 2A, the second interference film 120 is located between the first transparent substrate 101 and the second transparent substrate 102, and the first transparent substrate 101 is located between the first interference film 110 and the second interference film 120. However, in other embodiments, such as the optical filter assembly 200B of the light source device 20B shown in fig. 2B (see fig. 2B), the first interference film 110 and the second interference film 120 are both located between the first transparent substrate 101 and the second transparent substrate 102, so that the light beam L1 enters the second interference film 120 from the second transparent substrate 102, enters the first transparent substrate 101 from the first interference film 110, and exits the optical filter assembly 200B from the first transparent substrate 101, as shown in fig. 2B.

In this embodiment, the ratio of the thicknesses of the first layer 111 and the adjacent second layer 112 may be the same as the ratio of the thicknesses of the third layer 123 and the adjacent fourth layer 124. For example, the ratio (ratio) of the thickness T1 of each first film layer 111 to the thickness T2 of each second film layer 112 stacked in sequence in the first interference film 110 may be the same as the ratio of the thickness T3 of each third film layer 123 to the thickness T4 of each fourth film layer 124 stacked in sequence in the second interference film 120. For another example, in four adjacent film layers of the first interference film 110, the first film layer 111: second film layer 112: first film layer 111: the thickness ratio of the second film layer 112 is 1: 2: 3: 6, and in four adjacent film layers of the second interference film 120, the third film layer 123: fourth film layer 124: third film layer 123: the thickness ratio of the fourth film layer 124 is also 1: 2: 3: 6. in addition, the thickness 110T of the first interference film 110 may not be equal to the thickness 120T of the second interference film 120, wherein the thickness T1 may not be equal to the thickness T3, and the thickness T2 may not be equal to the thickness T4.

Therefore, the first interference film 110 and the second interference film 120 both have the same film layer distribution, and the Optical Path Length (OPL) of the light beam L1 on the first interference film 110 is different from the Optical Path Length (OPL) of the light beam L1 on the second interference film 120, that is, the Optical Path Difference (OPD) generated by the light beam L1 on the first interference film 110 is different from the Optical Path Difference (OPD) generated by the light beam L1 on the second interference film 120. Therefore, the first interference film 110 and the second interference film 120 both change the phase (phase) of the partial light in the light beam L1, and the phase difference (phase shift) caused by the first interference film 110 to the light beam L1 is different from the phase difference caused by the second interference film 120 to the light beam L1, i.e., the interference (including constructive interference and destructive interference) of the light beam L1 in the first interference film 110 and the second interference film 120 is not the same.

Generally, the conventional interference filter usually generates ripple (ripple), which not only affects the filtering effect, but also reduces the precision and accuracy of the optical measuring instrument. In detail, when the conventional interference filter filters the light beam, the spectrum of the filtered light beam has a wavy curve, as shown in fig. 1B, and the wavy curve is a so-called ripple.

Please refer to fig. 1B, which is a schematic diagram of a spectrum of a light beam L1 after passing through the first interference film 110 and the second interference film 120, respectively. The curve C1 shown by a solid line represents the spectrum of the light beam L1 after being filtered by the first interference film 110 only, which contains the first ripple effect of the first interference film 110 on the light beam L1. A curve C2 shown by a dotted line represents the spectrum of the light beam L1 after being filtered by the second interference film 120 only, which contains the second ripple effect of the light beam L1 caused by the second interference film 120.

Both the first interference film 110 and the second interference film 120 have similar film layer structures, so the spectrums of the light beam L1 (i.e., the curves C1 and C2 in fig. 1B) generated by both the first interference film 110 and the second interference film 120 are similar to each other. For example, the ripples in the curves C1 and C2 have substantially the same or similar number of peaks and valleys, but the locations (whiteboards) and Full Width at Half Maximum (FWHM) of the peaks and valleys are significantly different.

In the present embodiment, the thickness T1 is greater than the thickness T3, and the thickness T2 is greater than the thickness T4, i.e., the thickness 110T of the first interference film 110 is greater than the thickness 120T of the second interference film 120. Therefore, the ripple (curve C1) generated by the first interference film 110 has a wider peak-to-valley at half height, and the ripple (curve C2) generated by the second interference film 120 has a narrower peak-to-valley at half height, so the curve C1 looks like the curve C2 extending in the horizontal direction, and the curve C2 looks like the curve C1 compressed in the horizontal direction. In addition, in a certain wavelength range, such as the wavelength range of 200 nm to 350 nm in fig. 1B, the peak of the curve C1 corresponds to the trough of the (aligning to) curve C2, and the trough of the curve C1 corresponds to the peak of the curve C2, so as to generate destructive interference, i.e., the first ripple effect and the second ripple effect can cancel each other, as shown in fig. 1C.

Referring to fig. 1B and fig. 1C, a curve C3 shown in fig. 1C represents the spectrum of the light beam L1 after sequentially passing through the second interference film 120 and the first interference film 110. The first ripple effect and the second ripple effect cancel each other due to destructive interference between the curve C1 and the curve C2 in the wavelength range of 200 nm to 350 nm, so that the ripple effect is reduced, and a smoother curve C3 is generated, while the portion of the curve C3 in the wavelength range of 200 nm to 350 nm is shaped to approximate a smooth horizontal line. Therefore, the spectrum of the light beam L1 filtered by the optical filter assembly 100 shows a relatively smooth distribution in a certain wavelength range (e.g., 200 nm to 350 nm). Compared with the conventional interference filter, the optical filter assembly 100 has a better filtering effect, and helps to improve the precision and accuracy of the optical measurement instrument.

Referring to fig. 1A, in the embodiment shown in fig. 1A, the first interference film 110 and the second interference film 120 are formed on the same substrate. Specifically, the optical filter assembly 100 further includes a first transparent substrate 101, and the first transparent substrate 101 may be a glass plate or a sapphire substrate (sapphire substrate). The first interference film 110 and the second interference film 120 are both formed on the first transparent substrate 101, wherein the first transparent substrate 101 is located between the first interference film 110 and the second interference film 120, and is also located on the transmission path of the light beam L1. That is, the first interference film 110 and the second interference film 120 are respectively formed on two opposite sides (sides) of the first transparent substrate 101, and the first interference film 110 and the second interference film 120 can contact the first transparent substrate 101.

Both the first interference film 110 and the second interference film 120 may be formed by deposition (deposition). For example, the first film layer 111 to the fourth film layer 124 may be formed by Chemical Vapor Deposition (CVD), and the first interference film 110 and the second interference film 120 may be formed in situ (from in situ). That is, the first interference film 110 and the second interference film 120 are formed in a vacuum environment of the same chamber (chamber), i.e., the first film 111, the second film 112, the third film 123 and the fourth film 124 are formed in situ.

Fig. 2A is a schematic cross-sectional view of a light source device according to another embodiment of the invention. Referring to fig. 2A, in the light source device 20a of the present embodiment, the optical filter assembly 200a is similar to the optical filter assembly 100 of the previous embodiment. For example, the optical filter assembly 200a includes a first interference film 110, a second interference film 120 and a first transparent substrate 101. However, unlike the optical filter assembly 100, the optical filter assembly 200a further includes a second transparent substrate 102, and the second interference film 120 is formed on the second transparent substrate 102, contacts the second transparent substrate 102, but is not formed on the first transparent substrate 101.

Specifically, the first interference film 110 is still formed on the first transparent substrate 101 to form the first interference filter 201, but the second interference film 120 is formed on the second transparent substrate 102 to form the second interference filter 202. Therefore, the first interference film 110 and the second interference film 120 are respectively formed on two different transparent substrates, namely the first transparent substrate 101 and the second transparent substrate 102, and the optical filter assembly 200a includes at least two interference filters: a first interference filter 201 and a second interference filter 202. In addition, both the second transparent substrate 102 and the first transparent substrate 101 may be composed of the same material.

The first interference film 110, the second interference film 120, the first transparent substrate 101 and the second transparent substrate 102 are all located on the transmission path of the light beam L1, i.e. the light beam L1 sequentially penetrates through the second interference filter 202 and the first interference filter 201. The second interference film 120 is located between the first transparent substrate 101 and the second transparent substrate 102, and the first transparent substrate 101 is located between the first interference film 110 and the second interference film 120, so that the light beam L1 can enter the second interference film 120 from the second transparent substrate 102 and then enter the first interference film 110 from the first transparent substrate 101. The light beam L1 then exits the optical filter assembly 200a from the first interference film 110. In addition, the first interference filter 201 may be parallel to the second interference filter 202, so the light beam L1 may pass along both optical axes (optical axes) of the first interference filter 201 and the second interference filter 202.

It should be noted that "parallel" in the description of the invention and the claims of the present application includes "substantially parallel". In detail, when two substrates (for example, the first interference filter 201 and the second interference filter 202) are observed directly by the naked eye of a general person and are regarded as being parallel by most of the general persons without using a measuring tool such as a ruler or a protractor, the parallel is referred to as "substantially parallel". Therefore, it is generally considered that the first interference filter 201 and the second interference filter 202 are parallel when the first interference filter 201 and the second interference filter 202 are directly observed by naked eyes.

In the embodiments of fig. 2A and 2B, the thicknesses T1 of the layers of the first film 111 are the same as each other, the thicknesses T2 of the layers of the second film 112 are the same as each other, the thicknesses T3 of the layers of the third film 123 are the same as each other, and the thicknesses T4 of the layers of the fourth film 124 may be the same as each other, but the invention is not limited thereto. In other embodiments, the thicknesses of the various layers of the interference film may be different or partially the same. The skilled in the art can select different film design modes according to their needs, and the film design can refer to the third chapter in the aforementioned book "film optics and coating technology", and "illustration of optical film design", which will not be described herein again.

Referring to fig. 2C to 2F, schematic diagrams of optical film designs of first and second interference films according to another embodiment of the invention are shown. FIG. 2C shows odd layer thicknesses of the first interference film, and FIG. 2E shows even layer thicknesses of the first interference film. FIG. 2D shows odd layer thicknesses of the second interference film, and FIG. 2F shows even layer thicknesses of the second interference film. In fig. 2C to 2F, the horizontal axis is the film layer number, and the vertical axis is the film layer thickness. Referring to fig. 2C and 2E, the

film numbers

1, 3 and 5 … are alternately stacked with the film numbers 2, 4 and 6 … respectively, and the larger the film number is, the farther away from the transparent substrate is in the present embodiment. Conversely, the smaller the film layer number, the closer to the transparent substrate. In this embodiment, the total number of the first interference film layers is 100, the odd layers are made of the same first material, the even layers are made of the same second material, and the first material is different from the second material. The total number of the second interference film layers is 100, odd layers are made of the same first material, even layers are made of the same second material, and the first material is different from the second material.

The first interference film includes a first continuous film stack and the second interference film includes a second continuous film stack. In the present embodiment, the first continuous film stack is illustrated by the film numbered 1 to 39 in fig. 2C and 2E, and the second continuous film stack is illustrated by the film numbered 1 to 39 in fig. 2D and 2F. It should be noted that the thickness of the second film stack (film numbers 1 to 39) is 0.6 times the thickness of the first film stack (film numbers 1 to 39), respectively. However, in this embodiment, the layer numbers 40 to 100 in the first interference film and the layer numbers 40 to 100 in the second interference film do not have the same thickness ratio relationship. That is, the first continuous film stack accounts for 39% of the total number of layers in the first interference film, and the second continuous film stack accounts for 39% of the total number of layers in the second interference film. Similar to the previous embodiments, the continuous film stack (e.g., the first continuous film stack) accounting for 39% of the interference film can also improve the ripple problem. The 39% of this embodiment is only an alternative embodiment, and other ratios, such as 30% or more, may be used in other embodiments.

In addition, the first interference film may also include a first continuous film stack and a third continuous film stack, and the second interference film includes a second continuous film stack and a fourth continuous film stack. The thickness of each layer (first thickness distribution) of the first continuous film stack is in turn in a first ratio to the thickness of each layer (second thickness distribution) of the second continuous film stack. The thickness of each layer (third thickness distribution) of the third continuous film stack is in turn in a second ratio with the thickness of each layer (fourth thickness distribution) of the fourth continuous film stack, and the first ratio is different from the second ratio, so that the problem of ripple improvement can be achieved.

Fig. 2G to 2I are schematic diagrams of optical spectrums of optical filter assemblies according to various other embodiments of the present invention, wherein the optical filter assemblies corresponding to fig. 2G to 2I are respectively shown in the following tables.

Table one: the ratio of the first and second interference films is 0.98 (FIG. 2G)

Table two: the ratio of the layers was 0.98 except for the same thickness of 15 th layer (corresponding to FIG. 2H)

Table three: the layers 37-39 are of the same thickness, and the ratio of the other layers is 0.98 (corresponding to FIG. 2I)

Please refer to fig. 2G to fig. 2I. Fig. 2G and 2I are simulated spectra plotted according to the parameters listed in the above tables, wherein curve C21 represents the first interference film, curve C22 represents the second interference film, and curve C23 represents the spectrum after curves C21 and C22 interfere with each other, which is also equal to the result after curves C21 and C22 are superimposed. As shown in fig. 2G to 2I, the optical filter elements described in tables one to three exhibit a smoother spectrum (curve C23) after the wavelength 580 nm, i.e., the first and second ripple effects caused by the first and second interference films respectively cancel each other out, thereby reducing the ripple effect, and generating a smoother curve C23 as shown in fig. 2I. Thus, the optical filter assembly disclosed in the above table also has a better filtering effect, so as to improve the precision and accuracy of the optical measurement instrument.

Fig. 3 is a schematic cross-sectional view of a light source device according to another embodiment of the invention. Referring to fig. 3, the light source device 30 of the present embodiment is similar to the light source device 20a of the embodiment of fig. 2A. For example, the optical filter assembly 300 includes a first interference filter 201 and a second interference filter 202. However, unlike the optical filter assembly 200a in fig. 2A, the optical filter assembly 300 further includes a third interference filter 203. That is, the optical filter assembly 300 includes at least three interference filters, such as a first interference filter 201, a second interference filter 202, and a third interference filter 203, which are all on the transmission path of the light beam L1 and are parallel to each other, as shown in fig. 3.

Specifically, the optical filter assembly 300 includes a third transparent substrate 103 and a third interference film 130, wherein the third interference film 130 is formed on the third transparent substrate 103 to form a third interference filter 203. That is, the third interference filter 203 includes the third interference film 130 and the third transparent substrate 103. The third interference film 130 is also a multilayer film and includes a plurality of fifth film layers 135 and a plurality of sixth film layers 136, wherein the fifth film layers 135 and the sixth film layers 136 are alternately stacked. In addition, the optical path difference generated by the light beam L1 on the third interference film 130 is different from the optical path difference generated by the light beam L1 on the first interference film 110 or the second interference film 120.

Fifth layer 135 may be made of a high refractive index material and sixth layer 136 may be made of a low refractive index material, wherein fifth layer 135 may be made of the same material as first layer 111 and sixth layer 136 may be made of the same material as second layer 112. Therefore, the optical constants of the fifth layer 135 are the same as those of the first layer 111, and the optical constants of the sixth layer 136 are the same as those of the second layer 112. In addition, the fifth layer 135 and the sixth layer 136 may also be formed by deposition, such as Chemical Vapor Deposition (CVD). Therefore, the third interference film 130 is also formed by alternately stacking at least two film layers with different optical constants. In addition, in the present embodiment, the fifth film 135 is made of a high refractive index material and the sixth film 136 is made of a low refractive index material, but in other embodiments, the fifth film 135 may be made of a low refractive index material and the sixth film 136 may be made of a high refractive index material.

In the embodiment, each fifth layer 135 has a thickness T5, and each sixth layer 136 has a thickness T6, wherein the ratio of the thickness T5 of each fifth layer 135 to the thickness T6 of each sixth layer 136 stacked in sequence in the third interference film 130 may be the same as the ratio of the thickness of each layer stacked in sequence in the first interference film 110 and the second interference film 120. For example, in four adjacent film layers of the first interference film 110, the first film layer 111: second film layer 112: first film layer 111: the thickness ratio of the second film layer 112 is 1: 2: 3: 6, and of the four adjacent film layers of the third interference film 130, the fifth film layer 135: sixth film layer 136: fifth film layer 135: the thickness ratio of the sixth film layer 136 is also 1: 2: 3: 6. in addition, the thickness 130T of the third interference film 130 may not be equal to at least one of the thicknesses 110T and 120T, wherein at least one of the thicknesses T1 and T3 may not be equal to the thickness T5, and at least one of the thicknesses T2 and T4 may not be equal to the thickness T6.

Fig. 4A is a schematic cross-sectional view of a light source device according to another embodiment of the invention. Referring to fig. 4A, a light source device 40a of the present embodiment is similar to the light source device 20a of the embodiment of fig. 2A. For example, the optical filter assembly 400a also includes a first interference filter 201 and a second interference filter 202. The optical filter assembly 400a and the optical filter assembly 200a are different in that: the first interference filter 201 and the second interference filter 202 are neither parallel nor perpendicular, wherein the terms "non-parallel" and "non-perpendicular" as used in the description and the claims refer to the two substrates (e.g., the first interference filter 201 and the second interference filter 202) being apparently found to be neither parallel nor perpendicular by direct observation with the naked eye of a person without using a measuring tool such as a ruler or a protractor.

Although in fig. 2A and 4A, the light beam L1 penetrates through the first interference filter 201, since the first interference filter 201 and the second interference filter 202 are not parallel or perpendicular, the light beam L1 is not incident on the first interference filter 201 along the normal 201a of the first interference filter 201. Therefore, the optical path length of the light beam L1 in the first interference filter 201 in fig. 2A is different from the optical path length of the first interference filter 201 in fig. 4A, so that the optical path length difference generated by the first interference filter 201 in fig. 2A is different from the optical path length difference generated by the first interference filter 201 in fig. 4A. Therefore, for the same light beam L1, the filtering effects of the optical filter assembly 400a of fig. 4A and the optical filter assembly 200a of fig. 2A are different from each other.

An angle a1 between the normal 201a of the first interference filter 201 and the propagation path of the light beam L1 is described as an example of 30 degrees. In other embodiments, one skilled in the art can adjust angle a1 according to the desired ripple range. As shown in fig. 4A, it is apparent that the optical path length of the light beam L1 in the first interference filter 201 is related to the included angle a1, so the size of the included angle a1 can determine the optical path length difference of the first interference filter 201, and further control the filtering of the light beam L1 by the optical filter assembly 400 a. In addition, in the present embodiment, the first interference filter 201 may rotate with respect to the second interference filter 202. Thus, the rotation of the first interference filter 201 can adjust the filtering of the optical filter assembly 400 a.

Fig. 4B is a schematic cross-sectional view of a light source device according to another embodiment of the invention. Referring to fig. 4B, the light source device 40B in the embodiment of fig. 4B is similar to the light source device 40a in the embodiment of fig. 4A. In detail, the

optical filter assemblies

400b and 400a both include the same components, such as the first interference filter 201, and the difference therebetween is that: the optical filter assembly 400b includes two identical interference filters.

The optical filter assembly 400b comprises a first interference filter 201 and a second interference filter 402, wherein the second interference filter 402 comprises a second transparent substrate 102 and a second interference film 420, and the second interference film 420 is formed on the second transparent substrate 102. The second interference film 420 is the same as the first interference film 110, i.e. the second interference film 420 is also a multilayer film and includes a plurality of first film layers 111 and a plurality of second film layers 112 (not shown in fig. 4B). In addition, thickness 420t of second interference film 420 is equal to thickness 110t of first interference film 110. It can be seen that the second interference filter 402 is actually the first interference filter 201. That is, the optical filter assembly 400b substantially includes two identical interference filters (i.e., the first interference filter 201), wherein the second interference film 420 is formed in situ with the first interference film 110. In other words, in the embodiment, the optical filter assembly 400b can utilize two interference filters generated by the same batch of manufacturing processes, and improve the original ripple problem of the filters by the configuration of the two interference filters (an included angle is generated between the two interference filters).

Although in the optical filter assembly 400b, the second interference filter 402 is the same as the first interference filter 201, since the second interference filter 402 is not parallel or perpendicular to the first interference filter 201, the optical path difference generated by the first interference film 110 is different from the optical path difference generated by the second interference film 420, wherein the included angle a1 between the normal 201a of the first interference filter 201 and the transmission path of the light beam L1 may be greater than or equal to 0 degree and smaller than 90 degrees. It should be noted that increasing the included angle reduces the proportion of light that passes through the filter and increases the proportion of light that is reflected off the filter. And may be greater than or equal to 0 degrees and less than or equal to 70 degrees in another embodiment. In addition, similar to the optical filter assembly 400a, the first interference filter 201 can also rotate relative to the second interference filter 402 to control the filtering of the optical filter assembly 400a, so as to filter out unwanted light.

In addition, since the second interference filter 402 is identical to the first interference filter 201 and the second interference film 420 and the first interference film 110 are formed in situ, when the light beam L1 is incident along the normal lines of both the second interference filter 402 and the first interference filter 201, ripple effects generated by both the second interference filter 402 and the first interference filter 201 are substantially the same. However, since the second interference filter 402 is not parallel or perpendicular to the first interference filter 201, so that the optical path difference generated by the first interference film 110 is different from the optical path difference generated by the second interference film 420, the second interference filter 402 and the first interference filter 201 can generate different ripple effects which are mutually offset by adjusting the included angle a1, thereby reducing the ripple effect.

It should be noted that in the embodiments shown in fig. 4A and 4B, each of the optical filter assemblies 400a and 400B includes two interference filters, but in other embodiments, an additional interference filter may be added to the optical filter assembly 400a or 400B, such as the optical filter assembly 400C shown in the embodiment of fig. 4C. Referring to fig. 4C, the light filter assembly 400C of the light source device 40C includes at least three interference filters: a first interference filter 201, a second interference filter 202 and a third interference filter 203, wherein the third interference filter 203 is parallel to the first interference filter 201 or the second interference filter 202. Taking fig. 4C as an example, the third interference filter 203 is parallel to the second interference filter 202, but not parallel or perpendicular to the first interference filter 201.

In the embodiment shown in fig. 4C, the first interference filter 201, the second interference filter 202 and the third interference filter 203 comprised by the optical filter assembly 400C are all different interference filters, and the thicknesses of the interference films of the three interference filters are all unequal according to the description of the previous embodiments. However, in other embodiments, the optical filter assembly 400c may include at least two identical interference filters. Therefore, at least one of the first interference filter 201, the second interference filter 202 and the third interference filter 203 shown in fig. 4C can be replaced, so that the optical filter assembly 400C includes at least two identical interference filters.

For example, the second interference filter 202 in fig. 4C may be replaced by the second interference filter 402 of fig. 4B, so that the optical filter assembly 400C comprises two identical interference filters. Alternatively, the second interference filter 202 and the third interference filter 203 in fig. 4C may be replaced by the first interference filter 201, so that the optical filter assembly 400C includes three identical interference filters (i.e., the first interference filter 201).

In the embodiment shown in fig. 4C, the first interference filter 201 is located between the second interference filter 202 and the third interference filter 203 and is neither parallel nor perpendicular to the second interference filter 202 and the third interference filter 203, but in other embodiments the configuration (arrangement) of the first interference filter 201, the second interference filter 202 and the third interference filter 203 may vary. For example, the second interference filter 202 is located between the first interference filter 201 and the third interference filter 203, and is not parallel nor perpendicular to the first interference filter 201 and the third interference filter 203. Alternatively, the third interference filter 203 is located between the first interference filter 201 and the second interference filter 202, and the second interference filter 202 is not parallel or perpendicular to the first interference filter 201 and the third interference filter 203. Therefore, fig. 4C is for illustration only, and does not limit the arrangement of the first interference filter 201, the second interference filter 202, and the third interference filter 203.

In particular, in the above embodiments, the thicknesses of the interference films (e.g., the thickness 110t of the first interference film 110) included in the optical filter elements 100 to 400c are uniform, and the thickness ratios of the layers (e.g., the first to

fourth layers

111, 112, 123 and 124) may be the same, which means "substantially uniform" and "substantially the same". In detail, in the process of fabricating the interference film, it is difficult to avoid the situation that the thickness of the layers (e.g., the first layer 111) in the interference film has an error (tolerance) due to the limitation of the fabrication equipment, so that the observed interference film has a non-uniform thickness in a microscopic view, and the thickness ratios of the layers are different (e.g., the thickness ratio of the first layer 111 to the adjacent second layer 112 is not the same as the thickness ratio of the third layer 123 to the adjacent fourth layer 124), but the non-intentionally generated non-uniform thickness and different thickness ratios do not substantially affect the filtering effect of the optical filter elements 100 to 400c, and the aforementioned "thickness is substantially uniform" covers the non-uniform thickness, and the "thickness ratio is substantially the same" covers the different thickness ratios. However, in other embodiments of the optical filter assembly, the interference film may have a non-uniform thickness that is intentionally made, as shown in FIG. 5A.

Fig. 5A is a schematic cross-sectional view of a light source device according to another embodiment of the invention. Referring to fig. 5A, in the light source device 50, the light filter assembly 500 includes a first interference film 510, a first transparent substrate 101, and a second interference film 520, wherein the second interference film 520 may be the interference film of the previous embodiments, such as the first interference film 110, the second interference film 120, or the third interference film 130, and the first transparent substrate 101 is located between the first interference film 510 and the second interference film 520. Unlike the previous embodiment, the thickness of the first interference film 510 is not uniform, as shown in fig. 5A.

The first interference film 510 is also a multilayer film and includes a plurality of first film layers 511 and a plurality of second film layers 512, wherein the first film layers 511 and the second film layers 512 are stacked alternately, and the constituent materials of both the first film layers 511 and the second film layers 512 may be the same as the constituent materials of both the first film layers 111 and the second film layers 112. The first interference film 510 has a first side S1 and a second side S2 opposite to the first side S1, and the thickness of the first interference film 510 decreases from the first side S1 to the second side S2, so that an included surface is formed on the top surface of the first interference film 510, as shown in fig. 5A. In addition, the method of forming the first interference film 510 may include deposition, such as physical vapor deposition. During the cvd process, the first transparent substrate 101 may be tilted or a shield (shutter) may be used to shield the plating source to form the first interference film 510 with non-uniform thickness.

When the light beam L1 enters the first interference film 510, the optical paths of at least two light rays in the light beam L1 in the first interference film 510 are different. Taking fig. 5A as an example, in the light beam L1, the optical path length near the second side S2 is smaller than the optical path length near the first side S1. Therefore, the optical paths of the light beam L1 generated by the first interference film 510 are not uniform, so that the first interference film 510 not only can interfere the light beam L1 to filter the light beam L1, but also can compensate the light beam L1 that just penetrates through the second interference film 520 to reduce the influence of ripple.

Referring to fig. 5A, 5B and 5C, since the thickness of the first interference film 510 decreases from the first side S1 to the second side S2, after the light beam L1 passes through the first interference film 510, a plurality of light rays in the light beam L1 generate a plurality of mutually different spectrums in a plurality of different portions (sections) of the first interference film 510, such as a plurality of mutually different curves C5 shown in fig. 5B, wherein the curves C5 respectively have a plurality of different ripple effects of the first interference film 510 on the light beam L1. As described above with respect to the embodiment of FIGS. 1B and 1C, the different curves C5 in FIG. 5B overlap each other, thereby interfering to form a smoother spectrum, such as curve C6 in FIG. 5C. Specifically, in fig. 5C, the curves C5 in the wavelength range of 300 nm to 500 nm generate destructive interference, so that the ripple effects of the curves C5 cancel each other out, thereby reducing the influence of ripple, thereby generating a curve C6 having a shape that is a nearly smooth horizontal line in the wavelength range of 300 nm to 500 nm.

Referring to fig. 6, a light source device 60 according to an embodiment of the invention is shown, which includes a light filter assembly 600, wherein the light filter assembly 600 has similar functions as the light source device according to the previous embodiment. The optical filter assembly 600 includes a first interference filter and a second interference filter. Taking fig. 6 as an example, the first interference filter is an interference filter 610, and the second interference filter is an interference filter 206, wherein the interference filter 206 includes a transparent substrate 602 and an interference film 620 formed on the transparent substrate 602. The interference film 620 is one of the first interference film 110, the second interference film 120 and the third interference film 130 in the foregoing embodiment, and the transparent substrate 602 is also one of the first transparent substrate 101, the second transparent substrate 102 and the third transparent substrate 103 in the foregoing embodiment. Thus, the interference filter 206 may be the first interference filter 201, the second interference filter 202 or the third interference filter 203 in the aforementioned embodiments.

It can be seen that the interference filter 610 can be applied to the

light filter assemblies

200a, 200b, 300, 400a, 400b, or 400c of the aforementioned embodiments. In detail, in the embodiment shown in fig. 2A to 4C, one of the first interference filter 201, the second interference filters 202, 402 and the third interference filter 203 may be replaced with an interference filter 610. In addition, both the optical filter assembly 100 in fig. 1A and the optical filter assembly 500 in fig. 5A may further include at least one of the first interference filter 201, the second interference filters 202 and 402, the third interference filter 203, and the interference filter 610, so that each of the optical filter assembly 100 in fig. 1A and the optical filter assembly 500 in fig. 5A may include more than three layers of interference films.

In summary, the optical filter assembly of an embodiment of the invention includes at least two interference films having similar film layer structures, and can generate different optical path differences and interferences to improve the filtering effect. For example, when the optical filtering component filters the light beam, the optical filtering component enables the filtered light beam to have a spectrum with smoothly distributed intensity, so as to reduce the influence of ripple, thereby helping to improve precision and accuracy. The optical path difference can be generated by, for example, different coating thicknesses of the two interference films and/or gradually changing thicknesses and/or an included angle between the two interference sheets.

Although the present invention has been described with reference to the above embodiments, it should be understood that the invention is not limited to the above embodiments, and that various changes and modifications can be made by those skilled in the art without departing from the scope of the invention.

Claims

1. An optical filter assembly, comprising:

a first interference film including a plurality of first film layers and a plurality of second film layers, wherein the first film layers and the second film layers are alternately stacked;

a second interference film including a plurality of third film layers and a plurality of fourth film layers, wherein the third film layers and the fourth film layers are alternately stacked, the refractive index of the first film layer is the same as that of the third film layer, the refractive index of the second film layer is the same as that of the fourth film layer, the first interference film and the second interference film are both located on a transmission path of a light beam, and an optical path difference generated by the light beam on the first interference film is different from an optical path difference generated by the light beam on the second interference film;

a first transparent substrate located on the transmission path of the light beam, wherein the first interference film is formed on the first transparent substrate to form a first interference filter; and

a second transparent substrate located on the transmission path of the light beam, wherein the second interference film is formed on the second transparent substrate to form a second interference filter, wherein the first interference filter is not parallel or perpendicular to the second interference filter,

wherein the first interference film comprises a first continuous film stack, the second interference film comprises a second continuous film stack, the first continuous film stack accounts for more than 30% of the total number of the first film layers and the second film layers in the first interference film, the second continuous film stack accounts for more than 30% of the total number of the third film layers and the fourth film layers in the second interference film, wherein the proportion of the thickness of each first film layer to the thickness of each second film layer in the first continuous film stack is the same as the proportion of the thickness of each third film layer to the thickness of each fourth film layer in the second continuous film stack,

wherein the first interference film generates a first ripple effect on the light beam, the second interference film generates a second ripple effect on the light beam, and the first ripple effect and the second ripple effect are mutually balanced.

2. The optical filter assembly of claim 1, wherein a ratio of a thickness of each of the first layers to a thickness of each of the second layers sequentially stacked in the first interference film is the same as a ratio of a thickness of each of the third layers to a thickness of each of the fourth layers sequentially stacked in the second interference film.

3. The optical filter assembly of claim 1, wherein the first interference filter is identical to the second interference filter.

4. An optical filter assembly as claimed in claim 1, characterized in that the first interference filter is rotatable in a vertical direction relative to the second interference filter.

5. The optical filter assembly of claim 1, wherein the first interference film has a thickness equal to a thickness of the second interference film.

6. The optical filter assembly of claim 1, further comprising:

a third interference filter, located on the transmission path of the light beam, and comprising:

a third transparent substrate; and

and a third interference film formed on the third transparent substrate and including a plurality of fifth film layers and a plurality of sixth film layers, wherein the fifth film layers and the sixth film layers are alternately stacked, the refractive index of the fifth film layers is the same as that of the first film layers, the refractive index of the sixth film layers is the same as that of the second film layers, the third interference film is located on a transmission path of the light beam, and an optical path difference generated by the light beam on the third interference film is different from an optical path difference generated by the light beam on the first interference film or the second interference film.

7. The optical filter assembly of claim 1, wherein the first interference film has a first side and a second side opposite to the first side, and the thickness of the first interference film decreases from the first side toward the second side.

8. The optical filter assembly of claim 1 wherein the first and second layers are produced by a same batch process, and the third and fourth layers are produced by a same batch process.

9. The optical filter assembly of claim 1, wherein the first interference film and the second interference film are produced by a same batch process.

10. The optical filter assembly of claim 1, wherein the first ripple effect and the second ripple effect cancel each other within a predetermined band.

11. A light source device, comprising:

a light source for emitting a light beam; and

the optical filter assembly of claim 1 disposed in a transmission path of the light beam.

12. The light source device of claim 11, wherein the first interference filter is identical to the second interference filter.

13. A light source device as claimed in claim 11, characterized in that the first interference filter is rotatable in a vertical direction relative to the second interference filter.

14. The light source device according to claim 11, wherein the first interference film generates a first ripple effect on the light beam, the second interference film generates a second ripple effect on the light beam, and the first ripple effect and the second ripple effect cancel each other.

15. An optical filter assembly, comprising:

a first interference film comprising a plurality of first film layers and a plurality of second film layers exhibiting a first thickness distribution, wherein the first film layers and the second film layers are alternately stacked one on another; and

a second interference film including a plurality of third film layers and a plurality of fourth film layers having a second thickness distribution, wherein the third film layers and the fourth film layers are alternately stacked, the refractive index of the first film layer is the same as the refractive index of the third film layer, the refractive index of the second film layer is the same as the refractive index of the fourth film layer, wherein the first film layers and the second film layers of the first thickness distribution sequentially have a thickness ratio with the third film layers and the fourth film layers of the second thickness distribution, the thickness ratio is a constant, the first interference film and the second interference film are both located on a transmission path of a light beam, and an optical path difference of the light beam generated by the first interference film is different from an optical path difference of the light beam generated by the second interference film;

a second transparent substrate located on the transmission path of the light beam, wherein the second interference film is formed on the second transparent substrate to form a second interference filter, the first interference filter is not parallel or perpendicular to the second interference filter,

16. The optical filter assembly of claim 15 wherein the constant is 1.

17. The optical filter assembly of claim 15 wherein the constant is not equal to 1.

18. The optical filter assembly of claim 15, wherein the first interference filter is identical to the second interference filter.

19. An optical filter assembly as claimed in claim 15, characterized in that the first interference filter is rotatable in a vertical direction relative to the second interference filter.